Which HTML snippet links back to the very top of a webpage?
<a id="top"></a> <!-- placed at the top of the page --> <a href="#top">back to top</a>
<a name="top"></a> <!-- placed at the top of the page --> <a href="#top">back to top</a>
<a href="#">back to top</a> <a href="#top">back to top</a>
<button href="#">back to top</button> <button href="#top">back to top</button>